1. Technical Field
The present invention relates in general to an improved disk drive and, in particular, to an improved system, method, and apparatus for a disk clamp that prevents fastener lubrication from migrating into undesired areas of a disk drive.
2. Description of the Related Art
Data access and storage systems typically comprise one or more storage devices that store data on magnetic or optical storage media. For example, a magnetic storage device is known as a direct access storage device (DASD) or a hard disk drive (HDD) and includes one or more disks and a disk controller to manage local operations concerning the disks. The hard disks themselves are usually made of aluminum alloy or a mixture of glass and ceramic, and are covered with a magnetic coating. Typically, one to six disks are stacked vertically on a common spindle that is turned by a disk drive motor at several thousand revolutions per minute (rpm).
A typical HDD also utilizes an actuator assembly. The actuator moves magnetic read/write heads to the desired location on the rotating disk so as to write information to or read data from that location. Within most HDDs, the magnetic read/write head is mounted on a slider. A slider generally serves to mechanically support the head and any electrical connections between the head and the rest of the disk drive system. The slider is aerodynamically shaped to glide over moving air in order to maintain a uniform distance from the surface of the rotating disk, thereby preventing the head from undesirably contacting the disk.
Typically, a slider is formed with an aerodynamic pattern of protrusions on its air bearing surface (ABS) that enables the slider to fly at a constant height close to the disk during operation of the disk drive. A slider is associated with each side of each platter and flies just over the platter's surface. Each slider is mounted on a suspension to form a head gimbal assembly (HGA). The HGA is then attached to a semi-rigid actuator arm that supports the entire head flying unit. Several semi-rigid arms may be combined to form a single movable unit having either a linear bearing or a rotary pivotal bearing system.
The head and arm assembly is linearly or pivotally moved utilizing a magnet/coil structure that is often called a voice coil motor (VCM). The stator of a VCM is mounted to a base plate or casting on which the spindle is also mounted. The base casting with its spindle, actuator VCM, and internal filtration system is then enclosed with a cover and seal assembly to ensure that no contaminants can enter and adversely affect the reliability of the slider flying over the disk.
When current is fed to the motor, the VCM develops force or torque that is substantially proportional to the applied current. The arm acceleration is therefore substantially proportional to the magnitude of the current. As the read/write head approaches a desired track, a reverse polarity signal is applied to the actuator, causing the signal to act as a brake, and ideally causing the read/write head to stop and settle directly over the desired track.
The attachment of the data storage disks to the hub of the spindle motor is accomplished via a disk clamp. The disk clamp retains the disks on the hub by attaching directly to the hub of the motor. A conventional disk clamp 11 (FIGS. 1 and 2) is typically secured to a spindle motor 13 with several screws 15. The clamp engages an adjacent disk 17 to axially restrain the disk 17 and other disks below it, as shown, via spacer rings 19.
Screws are important components in disk drives because they fasten different parts together by delivering load in an axial direction. Axial load is very sensitive to the surface finish of the screw. In order to deliver consistent axial load, screws have been either lubricated or coated/plated with special surface treatments. In terms of performance, lubricated screws tend to deliver more consistent axial load.
Unfortunately, both of these two types of screw load-improving solutions have their shortcomings. For example, plated screws generate undesirable particles when tightened which cause contamination problems. The lubricant for screws also generates contaminant particles, but less than that generated by the plated screws. However, lubricant tends to migrate in dynamic applications, such as the present case when used to join disk clamps and spindle motor hubs and then rotated at high speeds. Lubricant migration causes many types of head-disk interference problems. Thus, an improved system, method, and apparatus that prevents fastener lubrication from migrating into undesired areas of a disk drive would be desirable.